Much of the information presented in this summary is drawn from the U.S. Department of Energy’s (DOE) Building Energy Codes Program and the Building Codes Assistance Project (BCAP). For more detailed information about building energy codes, visit the DOE and BCAP websites.

In 2004, the governor signed SB 306 adopting the 2000 International Energy Conservation Code (IECC) for residential construction and American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE) Standard 90.1-1999 for commercial construction. SB 59, signed in July of 2009, strengthened Delaware's building code, requiring 2009 IECC for new detached one- and two-story family dwellings and all other new residential buildings three stories or less constructed after July 1, 2010. All other new construction built after July 1, 2010, including high-rise residential, must meet ASHRAE 90.1-2007. The bill further requires all new residential buildings constructed after December 31, 2025, and all new commercial buildings constructed after December 31, 2030 to be zero net energy capable. To be qualified as net zero energy capable, the building must be energy efficient enough that the building would consume zero energy if the building owner chose to install on-site generation.